Sunk Cost Fallacy

What is it?

The sunk cost fallacy is a deeply ingrained cognitive error where we continue a behavior or endeavor because of previously invested resources (time, money, effort) rather than evaluating future value objectively. Economically rational decision-making requires ignoring sunk costs since they cannot be recovered regardless of future choices. However, humans struggle with this concept due to loss aversion and a need to justify past decisions. The fallacy is amplified when investments are visible to others, making it harder to admit "failure" by stopping. Classic examples include the Concorde jet project (the "Concorde fallacy"), where governments continued investing billions despite clear evidence of commercial non-viability. In personal life, it manifests as staying in unfulfilling relationships, finishing bad books, or eating food you don't want just because you paid for it. Organizations often escalate commitment to failing projects, throwing good money after bad. Breaking free requires reframing the decision: ask not "how can I justify what I've spent?" but "if I were starting fresh today, would I choose this path?"